Motor Neurone Disease is 52% Genetic

In a new study, researchers at Trinity College Dublin have found 1 in every 347 men and 1 in every 436 women are likely to develop motor neurone disease (MND) during their lifetime. Involving 1117 people diagnosed with MND, this study is the largest of its kind thus far set to unravel the questions of “nature vs. nurture” in the development of the condition.

MND is an umbrella term for a group of diseases which exhibit progressive degeneration of the motor neurons, the nerve cells that control muscles, in the brain and spinal cord. Leading to the wasting away of the body’s muscles, these conditions lead to general weakness and increasing loss of mobility as well as difficulty with speech, swallowing and breathing. Mortality usually occurs within an average of 2-3 years from the condition’s onset (Condon: 2019).

Major findings from the study include that genetic factors account for roughlly 52% of its incidence. This means that other factors and exposures contribute almost equally to its occurrence, and thus that the risk of other family members developing it when one has it are relatively low. The study’s lead author, Dr Marie Ryan said, “The fact that 50% of the risk is found within our genes supports our ongoing search to identify the many interacting genes that contribute to the causes of motor neurone disease.”

The researchers also looked at those carrying genetic mutations known to be associated with MND. In Ireland, the condition appears to be the direct result of an abnormality in one gene: C9orf72, for around 10% of all cases. Dr Ryan and her team found that those who carried an abnormal copy of this gene and developed MND were likely to have inherited it from their mothers (Trinity College Dublin: 2019).

These findings add to existing knowledge that MND can cluster with other conditions such as dementia, bipolar disorder, autism and addiction disorders in around 30% of affected families. This in turn means that multiple genetic factors likely work together to manifest MND.

To conclude, new research has found that genetics contribute to roughly 52% of one’s risk of developing MND. Although significant, this means that the incidence of the disease is likely due to an interplay between genetic and environmental factors, rather than those purely genetic.